Yet another home insulation 'survey'

For the third time in the last 4/5 months, a team of, quite personable and friendly, people has called at my front door asking whether I was aware of the home insulation grant + enquiring whether I have had a survey of my house to assess for same. I asked who they were from - Miller Surveyors apparently - and I told them that I was completely au-fait with home insulation grants and would be giving them absolutely no information whatsoever - inculding whether or not I have had a home survey. They seemed to handle my obdurately unco-operative behaviour quite well, and with a smile informed me that if I didn't tell them whether I'd had a home survey, then another team would inevitably call round to ask the same thing. Whilst in total admiration for the tenacity of what seems to me to be a cold call sales pitch, I will give short shrift to the next set who call to 'help'.Unless you are interested in having a bunch of sales people crawling through your house to look for opportunities to sell you insulation, I would recommend a similar course of action to all!